Boron nitride (EN) is a chemically inert non-oxide ceramic material which has a multiplicity of uses based upon its electrical insulating property, corrosion resistance, high thermal conductivity and lubricity, A preferred use is as a filler material additive to a polymeric compound for use in semiconductor manufacture as an encapsulating material or to form a low viscosity thermosetting adhesive or in formulating a cosmetic material. As presently manufactured boron nitride is formed by a high temperature reaction between inorganic raw materials into a white powder composition of BN particles having an hexagonal structure similar to graphite in a platelet morphology. The platelet morphology is for many applications undesirable and of limited utility. A conventional powder composition of BN particles has the physical attributes of flour in terms of its inability to flow. Accordingly, when added as a filler to a polymer a blended material is formed having poor rheologial properties and at loaded concentrations above 30 wt. % BN the blended material is so viscous that it is difficult to dispense from a mechanical dispenser such as a syringe. The physical characteristics of the filled polymer are enhanced at loading concentrations above 30 wt. % BN. Accordingly, a powder composition of BN particles with an improved rheology for use as a filler at high loading concentrations would be desirable.
The surface morphology and shape of conventional platelet BN particles are modified in accordance with the present invention to form boron nitride agglomerated particles bound by an organic binder such that when filled into a polymeric compound at loading levels between 30 to 50 wt. % BN the viscosity of the filled composition remains below 300 cp and preferably below a viscosity of 250 cp.